The development of Industrial Internet of Things (IIoT) has been limited due to the shortage of spectrum resources. Based on cognitive radio (CR), cognitive IIoT (CIIoT) has been proposed to improve spectrum utilization via sensing and accessing the idle spectrum. To improve sensing and transmission performance of the CIIoT, a cluster-based CIIoT is proposed, wherein the cluster heads perform cooperative spectrum sensing to get available spectrum and the nodes transmit via Non-orthogonal Multiple Access (NOMA). The frame structure of the CIIoT is designed, and the spectrum access probability and average total throughput of the CIIoT are deduced. A joint resource optimization for sensing time, node powers and the number of clusters is formulated to maximize the average total throughput. The optimal solution is obtained via sensing and power optimization. The clustering algorithm and cluster head alternation are proposed to improve transmission performance and ensure energy balance, respectively. The simulations have indicated that the NOMA for the cluster-based CIIoT can better guarantee the transmission performance of each node, especially the node decoding first, than the traditional NOMA and OMA.

The thermal performance of rural building envelopes is mostly non-standardized in Northern China, resulting in significant heat loss. In this study, we take, as an example, the central area of Liaoning province, with the objective of proposing some low-cost and energy-efficient solutions. Through our investigations, we found that heating energy consumption was reduced by 20% and construction costs increased by less than CNY 8000 (USD 1108), which can be accepted by rural residents. In order to achieve this target, the NSGA-II algorithm integrated with Rhino + Grasshopper and EnergyPlus simulation kernel was used to establish a thermal performance optimization model for the heat transfer of rural building envelopes in this severe cold region. Among the above-calculated Pareto optimal solutions, the recommended thickness of insulation layers for room floors, roofs, and external walls was about 70 mm, 50 mm, and 40 mm, respectively. Furthermore, we tried to reduce the window-to-wall ratio as much as possible. Finally, based on both the lower building renovation cost and energy-saving rate, three technical solutions from which rural residents could select, according to their specific needs, are put forward.

The climate characteristics of the islands in the Nansha Islands of China are a typical marine climate including high temperature, high relative humidity, high salt content, strong solar radiation, and long sunshine. These can provide suitable conditions for mold reproduction on the surface of the wall in a building. Therefore, mildew pollution on the wall for a long time can easily damage the building’s structure. It does not only directly affect the appearance of the building, but also indirectly affects the indoor environment and human health. In this paper, dominant fungi in the residential buildings on thee Nansha Islands of China are Aspergillus, Penicillium, and Cladosporium. Critical lines of temperature and relative humidity for mould growth on the interior surfaces of island residential building envelopes have been given and discussed. The results show that the risk of mould growth on the wall with different materials, from low to high, is reinforced concrete, aerated concrete block, coral aggregate, brick, and wood. Furthermore, in order to prevent the room regulated by air conditioner from being contaminated by mould, indoor air temperature should be set variable and controlled between 26 °C and 28 °C, the relative humidity should be changed between 50% and 80%.